Solid state processing of industrial blades, edges and cutting elements

ABSTRACT

A system and method for friction stir processing of an industrial blade, wherein friction stir processing techniques are used to modify the properties of the industrial blade to thereby obtain superior edge retention and superior resistance to chipping.

CROSS REFERENCE TO RELATED APPLICATIONS

This document claims priority to and incorporates by reference all ofthe subject matter included in the provisional patent applicationshaving docket number 2992.SMII.PR with Ser. No. 60/556,050 and filedMar. 24, 2004, docket number 3043.SMII.PR with Ser. No. 60/573,707 andfiled May 21, 2004, docket number 3208.SMII.PR with Ser. No. 60/637,223and filed Dec. 17, 2004, and docket number 3212.SMII.PR with Ser. No.60/654,608 and filed Feb. 18, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to industrial blades. Morespecifically, the invention relates to a method for improvingcharacteristics of industrial blades, edges and cutting elements.

2. Description of Related Art

It should be understood that the present invention applies to any typeof industrial blade, edge, or cutting elements where sharpness, theability to remain sharp, and resistance to chipping are importantfeatures. Hereinafter, the terms “edge” and “cutting element” are to beconsidered included in the term “industrial blade.”

Sharpness and the ability to retain a sharp edge are just two importantcriteria for an industrial blade. It is often the case that industrialblades are smaller components of much larger systems. Other industrialblades are cutters, borers, milling blades, drill bits, openers,groovers, crushers, reamers, saw blades and knives of various sorts thatare used to perform various industrial applications in many differentindustries. Regardless of the industry, an industrial blade that canremain sharp and resist chipping for longer periods of time results insubstantial time and cost benefits.

It is noted that impact resistance and toughness is inversely related towear resistance and hardness for most industrial blade materials.Therefore, different industrial blades are typically required for impactapplications and sharpness applications.

Certain industrial blades have been specifically designed to withstandthe impact of cutting hard material without the edge chipping.Generally, increased impact toughness means lower RC hardness ascompared to the higher RC values of other industrial blades. As aresult, the ability to maintain a sharp edge (referred to hereinafter asedge retention) is compromised. A technique has been developed to testseveral different types of steel at different “Rockwell” or RC hardnessmeasurements until a happy medium is found between “good” edgeretention, where there is no dulling of the industrial blade, and theprevention of edge chipping.

When examining industrial blades, it is useful to examine analogousblades in the hand-held blade industry. For example, a conventional D2steel hand-held cleaver, such as a Brown Bear™ Cleaver, is designed toconsistently cut through bone without chipping. However, when a rope isrepeatedly cut with the hand-held cleaver, the edge retention istypically not up to par with harder hand-held knife blades, such as aJaeger™ Boning knife also sold by Knives of Alaska. Similarly, harderhand-held knife blades that offer increased edge retention in low impactcutting applications typically experience edge chipping when used to cutor chop through harder material such as hard wood and bone due to theincreased brittleness of the hand-held blade.

Ideally, an industrial blade, like a hand-held blade, would be able towithstand abrasive cutting and retain a sharp edge, yet be able towithstand the high impact necessary to chop through hard materialswithout the edge chipping or fracturing.

Accordingly, what is desired is an industrial blade that can withstandthe high impact of chopping or cutting through hard materials, and stillprovide superior edge retention.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method for enhancing themechanical properties of an industrial blade.

In another aspect the present invention provides an industrial bladehaving superior edge retention and a method for forming the same.

In another aspect, the invention provides a method for forming a cuttingedge on an industrial blade that will result in superior resistance tochipping.

In one embodiment, the present invention provides a system and methodfor friction stir processing of an industrial blade, wherein frictionstir processing techniques are used to modify the properties of theindustrial blade to thereby obtain superior edge retention and superiorresistance to chipping.

These and other aspects, features, advantages of the embodiments of thepresent invention will become apparent to those skilled in the art froma consideration of the following detailed description taken incombination with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of one tool that can be used to perform thefriction stir processing of the present invention.

FIG. 2 is a cross-sectional view of another tool that can be used toperform the friction stir processing of the present invention.

FIG. 3 is a cross-sectional view of another tool that can be used toperform the friction stir processing of the present invention.

FIG. 4 is a cross-sectional view of a material that is friction stirprocessed to modify the characteristics of the material.

FIG. 5 is a cross-sectional view of a material that is friction stirprocessed to modify the characteristics of the material, and having anoverlay identifying where a cutting edge could be formed from thefriction stir processed material.

FIG. 6 is a cross-sectional view of material that has been friction stirmixed so as to include another material.

FIG. 7 is a cross-sectional view of one embodiment for friction stirmixing an additive material 112 into another using a mesh or screen 110to hold the additive material 112 in place.

FIGS. 8-66 are various industrial blades.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the diagrams of the present invention inwhich the various elements of the present invention will be givennumerical designations and in which the invention will be discussed soas to enable one skilled in the art to make and use the invention. It isto be understood that the following description is only exemplary of theprinciples of the present invention, and should not be viewed asnarrowing the claims which follow.

In one aspect, the present invention provides a system and method forperforming friction stir processing on an industrial blade. The frictionstir processing can be performed in one embodiment on a surface of aworkpiece that is fashioned into the industrial blade. In anotherembodiment, the friction stir processing can be performed deeper intothe workpiece. In another embodiment, it is also possible to performfriction stir mixing wherein an additive element is mixed into thesurface or deeper into a workpiece using a friction stir mixing tool.

FIG. 1 is a perspective view of a tool being used for friction stirwelding that is characterized by a generally cylindrical tool 10 havinga shoulder 12 and a pin 14 extending outward from the shoulder. The pin14 is rotated against a workpiece 16 until sufficient heat is generated,at which point the pin of the tool is plunged into the plasticizedworkpiece material. The workpiece 16 is often two sheets or plates ofmaterial that are butted together at a joint line 18. The pin 14 isplunged into the workpiece 16 at the joint line 18. Although this toolhas been disclosed in the prior art, it will be explained that the toolcan be used for a new purpose.

Another embodiment of the present invention is to use a tool as shown inFIG. 2. FIG. 2 is a cross-sectional view of a cylindrical friction stirprocessing tool 20. The friction stir processing tool 20 has a shank 22and a shoulder 24, but no pin. Therefore, instead of plunging a pin intothe material to be solid state processed, the shoulder is pressedagainst the material. Penetration by the shoulder is typically going tobe restricted to the surface of the material or just below it because ofthe larger surface area of the shoulder as compared to the pin.

It should be noted that while the pin 16 of the tool 10 in FIG. 1 doesnot have to be plunged into the material, the pin is more likely to bedesigned for easy penetration. Thus, because the pin 16 is more likelyto have a very small surface area as compared to the tool 20 of FIG. 2,the pin is more likely to plunge into the material. However, it may beadvantageous to use the smaller surface area of the pin 16 forprocessing much smaller areas of a material, even just on the surfacethereof. Therefore, it is another embodiment of the present inventionthat surface and near-surface processing can also be accomplished usinga tool that is more typically used for penetration and joining ofmaterials.

FIG. 3 is provided as an alternative embodiment for a tool having nopin. FIG. 3 shows a tool 30 having a shank 32 that is smaller indiameter than the shoulder 34. This design can be more economicalbecause of less material used in its construction, depending upon thediameter of the shoulder 34.

It is important to recognize that nothing should be inferred from theshape of the shoulders 24 and 34 in FIGS. 2 and 3. The shoulders 24 and34 are shown for illustration purposes only, and their exactcross-sectional shapes can be modified to achieve specific results.

Experimental results have demonstrated that the material to be used forthe industrial blade may undergo several important changes duringfriction stir processing. These changes may include, but should not beconsidered limited to, the following: microstructure, macrostructure,toughness, hardness, grain boundaries, grain size, the distribution ofphases, ductility, superplasticity, change in nucleation site densities,compressibility, expandability, coefficient of friction, abrasionresistance, corrosion resistance, fatigue resistance, magneticproperties, strength, radiation absorption, and thermal conductivity.

Regarding nucleation, observations indicate that there may be morenucleation sites in the processed material due to the energy inducedinto the material from friction stir processing. Accordingly, more ofthe solute material may be able to come out of solution or precipitateto form higher densities of precipitates or second phases.

In FIG. 4, a section of ATS 34 steel was friction stir processed byplunging a tool similar to the tool shown in FIG. 2 into the workpiece70 and moving the tool transversely along a middle length thereof.Transverse movement would be perpendicular to the page, thus FIG. 5 is across-sectional view of the base material 70.

FIG. 4 shows that the tool plunged into the base material 70 from thetop 72. Several areas appearing as small circles are shown as havingbeen tested for hardness relative to the Rockwell scale in the variouszones of the base material. The stir zone 74 is shown having a hardnessof 60 RC. Close to the boundary of the inner TMAZ (thermallymechanically affected zone) and the outer HAZ (heat affected zone) thebase material 70 is shown as having a hardness value of 44 RC at alocation 76. Finally, an unprocessed or original base material zone isshown as having retained, in other samples, its original hardness valueof 12 RC at approximately location 78.

FIG. 5 is an illustration of an overlay 90 of a cutting edge on theATS-34 steel base material 70. The overlay 90 indicates one advantageousconfiguration of an industrial blade that could be machined from thematerial 70, wherein the configuration takes the greatest advantage ofthe improved toughness and hardness characteristics of the friction stirprocessed material 70. Note that the industrial blade overlay 90 isformed in the processed region 74 that will result in a hard and yettough cutting edge. Likewise, any object being formed from a processedmaterial can be arranged to provide the most advantageous propertieswhere it is most critical for the object. In this example, a beneficialcutting edge will be achieved from having an edge disposed well withinthe processed material.

As examples of what is possible to create using the system and methodsof the embodiments of the present invention, three hand-held bladesprocessed using a friction stir processing system and method inaccordance with the present invention were prepared and tested againstconventional blades. The creation of the test blades was accomplished byfriction stir processing a workpiece that was then finished to form ahand-held knife blade having a profile substantially identical to aconventional knife blade used for a comparison.

The hand-held test blades of the present invention were created bymachining the hand-held test blades in accordance with the followinginstructions. The first attempt at grinding was to obtain a 22 degreeangle with a 600 grit diamond belt. The result was a polished edge. A320 diamond grit was then used with good results to further refine thehand-held blade. The desired angle was established and after a fewpasses, the cutting edge was placed against the 600 grit diamond belt toestablish the desired wire “burr”. The wire burr was removed with an8,000 grit diamond belt and then polished with a 50,000 grit diamondbelt. A razor “shaving” edge was established on the test blades and thecutting edge appeared to remain totally within the processed material.

It should be noted that the instructions provided above are only tocreate test blades that are comparable in sharpness to the blades thatare being used for comparison purposes. An industrial blade that can becreated using the friction stir processing and friction stir mixingmethods of the present invention should not be considered to be limitedto the parameters stated above.

An important element of the present invention is also the concept offriction stir mixing. Whereas friction stir processing will be regardingas the processing of a single material that is to be fashioned into anindustrial blade, friction stir mixing provides for additional additivematerials to be included in the friction stir mixing process. Theadditive materials become an integral part of the resulting industrialblades.

FIG. 6 is a cross-sectional view of a base material that has beenfriction stir mixed so as to include another additive material.Specifically, a steel member 100 has been friction stir mixed so as towork in diamond particles 102 into the steel member.

FIG. 7 is a cross-sectional view of one embodiment for friction stirmixing an additive material 112 into another using a mesh or screen 110to hold the additive material 112 in place. Specifically, a stainlesssteel mesh or screen 110 is being used to hold carbide 112 in the formof a powder. The screen 110 and carbide powder 112 are disposed on thesurface of a base material 114. The surface of the base material 114 isthen friction stir processed, resulting in a mixing of the stainlesssteel 110, the carbide 112, and the base material 114 at the surface ofthe base material. Alternatively, the different materials could be mixedfurther into the base material 114 using a tool having a pin, or byusing a tool having a shoulder that is pressed harder into the basematerial.

An important concept of the present invention is that solid stateprocessing or friction stir processing that is performed is a temporarytransformation into a plasticized state. Thus, the material that is usedas the workpiece and formed into the industrial blade may not passthrough a liquid state.

The balance of this document is devoted to test results for comparisonsthat achieved unexpected results using hand-held blades. For comparisonpurposes, a Brown Bear™ hand-held Cleaver blade formed of D-2 steel wasbolted to a test handle. A hand-held test blade having a cutting edgeformed of friction stir processed D-2 steel ground to an identicalprofile was also prepared and bolted to a handle in a similar manner.The resulting hand-held cleaver blade and hand-held test blade were both24 ounce blades that provided ample weight and inertia for chopping.

A first chopping test was performed on a green red oak limb; a secondchopping test was performed on a dried Osage orange limb, which is anextremely hard, dense wood; a third chopping test was performed on anelk antler (bone); a fourth chopping test was performed on a brickblock, and a fifth chopping test was performed on a steel anvil. Resultsfor chopping with the test blade are as follows in Table 1: TABLE 1 TestResult Green red oak No edge chipping; edge will still shave dry hairDried Osage No edge chipping; edge will still Orange shave dry hair Elkantler No edge chipping; minor edge wear evident; would shave wet hairBrick Edge damage evident with several small chips and dulled edge Steelanvil Small edge separation at point of machining groove for frictionstir

Both hand-held cleavers were able to consistently cut through bone andhard wood without chipping. However, the hand-held test blade was foundto provide greater edge retention over the conventional hand-heldcleaver.

The above tests were also performed using a hand-held Bush™ Camp Knifeand a hand-held Jaeger™ Boning knife which both have good edge retentionwhen compared to other hand-held knives. As shown in FIG. 16, bothhand-held knives had catastrophic cutting edge failures when tested onthe elk antler and, thus, were not tested on the harder materials.

A second hand-held test blade was sharpened to perform new tests. Thesecond test blade was used to cut rope for 30 minutes. In that time, 607cuts were made until the rope was gone. The second hand-held test bladestill shaved dry hair afterwards.

Further tests were performed on hand-held test blades, such as thesharpness test of the friction stir processed edge. For this test, fivedifferent Knives of Alaska™, Inc. hand-held knife models were firsttested. These hand-held knives include the Alaskan Brown BearSkinner/Cleaver (D2 steel; RC 55-57), the Jaeger Boning Knife (ATS-34steel; RC 59-61), the Bush Camp Knife (AUS8 steel; RC 57-59), the Cohofisherman's knife (hollow ground AUS8 steel; RC 57-59), and the MagnumUlu (D2 steel; RC 59-61). The final test was on a hand-held test bladewith the friction stir processed edge.

The test for sharpness involved placing a ¾ inch thick hemp rope on a2×6 board. A section on each knife was selected and the rope was cutcompletely through by striking the back of the blade with a soft mallet.The rope was repeatedly cut, at the same point on the hand-held knifeblade. The number of cuts was recorded for each hand-held blade. Whenthe hand-held knife's tested section would no longer shave dry hair onthe tester's arm—this was recorded as one past the maximum number ofcuts that that hand-held blade steel would retain a shaving edge. Thetest results are as follows as shown in Table 2: TABLE 2 Number of CutsWhere hand-held Hand-held Knife Knife No Longer Shaves Alaskan BrownBear 17 Jaeger Boning Knife 67 Bush Camp Knife 41 Coho Fisherman's Knife14 Magnum Ulu 52 Test Blade 100+

It is observed that the testing of the hand-held test blade was stoppedat 100 cuts as the hand-held test blade was already exceeding all othertest samples. The hand-held test blade is shown in FIG. 15. Furthermore,the hand-held blade would still shave and there was no appreciabledifference between the edge when the testing began and after 100 cuts.

The test blades formed in accordance with the present invention held upto and exceeded expectations in the sharpness category and in the impacttest results. Conventionally, it is unexpected to be able to take a twopound hand-held test blade and swing it smartly to cut through a hardmaterial such as elk antler, repeatedly, and still retain a shaving edgewith no edge fracturing. Such performance is unheard of in the hand-heldknife industry.

Friction stir processing may be applied to any hand-held knife blade toenhance performance characteristics of the blades. Such hand-held knifeblades may be formed of any material known in the art, including D2steel, ATS-34 steel, AUS8 steel, S-30V steel, or other materials.

FIGS. 8-66 are provided as illustrations of the many different types ofindustrial blades that are considered to be within the scope of theembodiments of the present invention. However, the following list ofindustrial blades should not be considered limiting, as there are otherindustrial blades that can also take advantage of the benefits of theembodiments of the present invention.

FIGS. 8-66 includes the following industrial blades: angle millingcutter, boring tools, broach, burr, chanfer cutter, circular cuttingblades for food, metal or paper, converting slitters, counter bores,counter sinks, cutting tool endmill, cutting tool reamer, deburringtool, drill bit, endmill, fishing milling cutter, food processing, formcutter, gear cutting tool, gear shaper tool-shaving cutter, groovingtool, guillotine paper and food cutting blades, gun drill and reamers,helical end mill, hobs, hobs and side milling cutters, hole opener, holesaw, hydraulic pipe cutter, jaw crusher, keyseat cutter, metal workingshear blades, milling cutter, packaging and cutoff knives, plasticgranulating knives, press brake dies, reamer, rotaryfile cutter, roundtextile knife, router bit, saw blades, shear blades, shell end mills,side milling cutter, slitter blades for packaging, tap cutter, taps,textile knives, thin disk cutters, thread mill, and threading tool. Thislist of industrial blades should not be considered limiting, butpresents a large cross-section of the various industrial blades on themarket.

It is to be understood that the above-described arrangements are onlyillustrative of the application of the principles of the presentinvention. Numerous modifications and alternative arrangements may bedevised by those skilled in the art without departing from the spiritand scope of the present invention. The appended claims are intended tocover such modifications and arrangements.

1. A method for creating an industrial blade, said method comprising thesteps of: 1) providing a high melting temperature workpiece that is tobe formed into an industrial blade; 2) providing a friction stirprocessing tool that includes a higher melting temperature material thanthe workpiece on a portion thereof; and 3) friction stir processing theworkpiece using the tool to thereby modify characteristics thereof; and4) forming the industrial blade from the workpiece.
 2. The method asdefined in claim 1 wherein the method further comprises the step ofcausing a substantially solid state transformation without passingthough a liquid state of the workpiece.
 3. The method as defined inclaim 1 wherein the step of providing the high melting temperatureworkpiece includes selecting the high melting temperature workpiece fromthe group of high melting temperature materials including ferrousalloys, non-ferrous materials, superalloys, titanium, cobalt alloystypically used for hard-facing, and air hardened or high speed steels.4. The method as defined in claim 1 wherein the method further comprisesthe step of synthesizing a new material from solid state processing ofthe workpiece, wherein the new material has characteristics that areadvantageous to an industrial blade.
 5. The method as defined in claim 1wherein the method further comprises the steps of: 1) providing anadditive material; and 2) friction stir mixing an additive material intothe workpiece to thereby modify at least one characteristic of theworkpiece.
 6. The method as defined in claim 1 wherein the methodfurther comprises the step of modifying a microstructure of theworkpiece.
 7. The method as defined in claim 6 wherein the methodfurther comprises the step of modifying a macrostructure of theworkpiece.
 8. The method as defined in claim 7 wherein the step ofmodifying the microstructure includes increasing toughness of theworkpiece.
 9. The method as defined in claim 7 wherein the step ofmodifying the microstructure includes increasing or decreasing hardnessof the workpiece.
 10. The method as defined in claim 7 wherein the stepof modifying the microstructure includes increasing or decreasingstrength of the workpiece.
 11. The method as defined in claim 7 whereinthe step of modifying the microstructure includes friction stirprocessing the workpiece to thereby obtain superior edge retention onthe industrial blade that is formed therefrom.
 12. The method as definedin claim 7 wherein the step of modifying the microstructure includesfriction stir processing the workpiece to thereby obtain superiorresistance to chipping on the industrial blade that is formed therefrom.13. The method as defined in claim 1 wherein the step of providing thefriction stir processing tool further includes the step of providing thefriction stir processing tool having a shank, a shoulder and a pin. 14.The method as defined in claim 13 wherein the step of providing thefriction stir processing tool having a shank, a shoulder and a pinfurther comprises the step of including a superabrasive material. 15.The method as defined in claim 15 wherein the method further comprisesthe step of friction stir processing without plunging the pin into theworkpiece.
 16. The method as defined in claim 1 wherein the step ofproviding the friction stir processing tool further includes the step ofproviding the friction stir processing tool having a shank and ashoulder.
 17. A hand-held knife with a blade having improved edgeretention and resistance to chipping, said industrial blade comprised ofa high melting temperature workpiece, wherein the high meltingtemperature workpiece is created through friction stir processing.
 18. Asystem for manufacturing a hand-held knife blade through friction stirprocessing, said system comprised of: a high melting temperatureworkpiece; and a friction stir processing tool that includes a highermelting temperature material than the workpiece on a portion thereof,wherein the tool is used to perform friction stir processing to therebycause solid state transformation of the workpiece, whereincharacteristics of the workpiece are modified.
 19. The system as definedin claim 18 wherein the tool is further comprised of a shank, a shoulderand a pin.
 20. The system as defined in claim 18 wherein the tool isfurther comprised of a shank and a shoulder.